PKCδ knockdown inhibits free fatty acid induction of endothelial cell apoptosis.

The mechanisms whereby free fatty acids induce endothelial cell apoptosis are not yet understood. The present study aimed to investigate the role of PKCδ in free fatty acid-induced endothelial cell apoptosis. In addition, we looked for evidence of apoptosis-related interactions between PKCδ and Fas signal pathway. Human umbilical vein endothelial cells were treated with various concentrations of free fatty acids and transiently transfected with PKCδ siRNA or Fas siRNA to inhibit PKCδ or Fas expression. Cell proliferation was determined through colorimetric assays, and apoptosis was quantified using flow cytometry. Protein expression was determined from cell lysates using Western blots with antibodies against p-PKCδTyr512, PKCδ, and Fas. Statistical analyses were performed. Free fatty acids had multiple effects on human umbilical vein endothelial cells, including concentration-dependent inhibition of cell proliferation, induction of apoptosis, increased Fas expression, and increased PKCδ expression and phosphorylation. Inhibition of PKCδ mRNA expression by PKCδ siRNA led to a reduction in both free fatty acid-induced apoptosis and Fas expression. However, Fas siRNA treatment inhibited Fas, but not PKCδ, expression in human umbilical vein endothelial cells. The free fatty acid-induced apoptosis in endothelial cells are possibly mediated by PKCδ and may involve upregulation of its downstream Fas.